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# Speedy Sidney

*(Apologies to bee lovers everywhere!)*

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Age 11 to 14

Challenge Level

- Problem
- Student Solutions

Two trains set off at the same time from each end of a single straight railway line which is 100 km long.

The first train travels at a constant speed of 55 km/h. The second train travels at a constant speed of 70 km/h.

A very fast bee, Sidney travels at 100 km/h. Sidney starts off in front of the first train and flies continuously back and forth between the two trains.

How far does Sidney fly before he is squashed between the two trains?

Extension:

How could you alter the problem so that Sidney flies exactly 100
km?

A security camera, taking pictures each half a second, films a cyclist going by. In the film, the cyclist appears to go forward while the wheels appear to go backwards. Why?

How far have these students walked by the time the teacher's car reaches them after their bus broke down?

A train leaves on time. After it has gone 8 miles (at 33mph) the driver looks at his watch and sees that the hour hand is exactly over the minute hand. When did the train leave the station?